Stable Escherichia coli-Clostridium acetobutylicum shuttle vector for secretion of murine tumor necrosis factor alpha.

Recombinant plasmids were constructed to secrete mouse tumor necrosis factor alpha (mTNF-alpha) from Clostridium acetobutylicum. The shuttle plasmids contained the clostridial endo-beta1, 4-glucanase (eglA) promoter and signal sequence that was fused in frame to the mTNF-alpha cDNA. The construction was first tested in Escherichia coli and then introduced in C. acetobutylicum DSM792 by electroporation. Controls confirmed the presence and stability of the recombinant plasmids in this organism. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and an in vitro cytotoxic assay were used to monitor expression and secretion of mTNF-alpha during growth. Significant levels of biologically active mTNF-alpha were measured in both lysates and supernatants. The present report deals with investigations on the elaboration of a gene transfer system for cancer treatment using anaerobic bacteria.